The configuration of a unit pixel of a prior-art EL display device is shown in FIGS. 32 and 33. In FIGS. 32 and 33, reference symbol GL indicates a gate line, reference numeral 13 indicates an auxiliary capacitor, reference symbol SL indicates a source line, reference numeral 11 indicates an EL element, reference symbol Tr1 indicates a switching transistor, reference symbol Tr2 indicates a driver transistor, and reference numeral 70 indicates a current-supplying line for supplying a current to the EL element 11. The EL element 11 emits light as follows. First, when the gate line GL and the source line SL are both turned on, an electric charge is stored in the auxiliary capacitor 13 via the switching transistor Tr1. Since the auxiliary capacitor 13 continues to apply a voltage to a gate of the driver transistor Tr2, even when the switching transistor Tr1 is turned off, a current continues to flow from the current-supplying line 70 to the EL element 11, and thus the EL element is driven to emit light by a current in response to the current image signal, until an image signal is written in the present frame.
In the above prior-art example, the EL element continues to emit light during one frame period. Thus, when displaying a moving image, due to an after-image phenomenon, an image of the previous frame is superimposed over an image of the present frame, and accordingly the image observer perceives the image to be fuzzy (see 2001 FPD Technology Outlook, p. 122).
As a solution to such a case, it is known that by inserting a blanking period (which means a period where light emission of the EL elements stop and the entire screen goes into a black display state) while an image of one frame is displayed, an after-image is suppressed, clarifying the image.
Based on such a concept, Japanese Unexamined Patent Publication No. 2000-221942 discloses a configuration in which transistors dedicated to providing blanking signals are provided and the blanking signals are turned on at a given time immediately before the next one frame period starts.
The above-described configuration, however, requires a dedicated transistor for each pixel and controlling lines for providing blanking signals. Thus, an increase in the area occupied by the dedicated transistors and controlling lines reduces the aperture ratio of the pixels. In addition, additional provision of the dedicated transistors and controlling lines brings about a reduction in yield of panels.